Adding the PPA gives me this error "signature not checked due to a missing key"

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1

I am on Linux Mint 20.1
When ever I try to add the PPA so I can install Lutris it gives me this error. Any ideas how I can fix this?

Thank you.

Executing: /tmp/apt-key-gpghome.EYAFMnsnlP/gpg.1.sh --keyserver hkps://keyserver.ubuntu.com:443 --recv-keys 82D96E430A1F1C0F0502747E37B90EDD4E3EFAE4
gpg: key 37B90EDD4E3EFAE4: public key "Launchpad PPA for lutris" imported
gpg: Total number processed: 1
gpg:               imported: 1
gpg: invalid key resource URL '/tmp/apt-key-gpghome.EYAFMnsnlP/home:ungoogled_chromium.asc.gpg'
gpg: keyblock resource '(null)': General error
gpg: key 1DCC29D5F18761E8: 1 signature not checked due to a missing key
gpg: key 02456C79B2FD48BF: 1 signature not checked due to a missing key
gpg: key A6616109451BBBF2: 12 signatures not checked due to missing keys
gpg: key 3B4FE6ACC0B21F32: 3 signatures not checked due to missing keys
gpg: key D94AA3F0EFE21092: 3 signatures not checked due to missing keys
gpg: key C8CAB6595FDFF622: 2 signatures not checked due to missing keys
gpg: key 871920D1991BC93C: 1 signature not checked due to a missing key
gpg: Total number processed: 11
gpg:       skipped new keys: 11

sudo apt update

 The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 37B90EDD4E3EFAE4
Reading package lists... Done
W: GPG error: http://ppa.launchpad.net/lutris-team/lutris/ubuntu focal InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 37B90EDD4E3EFAE4
E: The repository 'http://ppa.launchpad.net/lutris-team/lutris/ubuntu focal InRelease' is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.
2

hello, edit /etc/apt/sources.list and remove all lutris related lines.

then did a
apt update
and

sudo add-apt-repository ppa:lutris-team/lutris
sudo apt update
sudo apt install lutris

3

Hi. A bit late to the party but this should fix your issues.

Run sudo apt-get update

This should go through the list of repos and try update each of them. When it reaches the lutris ppa it will give you a warning about the missing key . For me it was

Err:10 http://ppa.launchpad.net/lutris-team/lutris/ubuntu focal InRelease The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 37B90EDD4E3EFAE4

For you that HEX at the end will be different. Make a note of it.

Now run sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys <insert hex here>

for me it was

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 37B90EDD4E3EFAE4

Now run sudo apt update again and it should fech data from the lutris ppa.

You should now be able to run sudo apt install lutris